1. Field of the Invention
The present invention relates to a data processing apparatus, and a control method thereof.
2. Description of the Related Art
In general, in a digital camera, shot image data obtained by shooting is assigned a file name according to the rule of DCF (Design rule for Camera File system), for example, a file name IMG_XXXX.jpg (XXXX is a numeral which increments in the shooting order). However, when files named by such a naming rule are copied to and managed by an external device, file names often are not unique. In such a state, when a file is copied to an external device, an old file may be overwritten.
For this reason, a technique for associating unique identification information (to be referred to as unique ID hereinafter) used to specify an image so as to improve image searchability and management between a digital camera and external device to which the digital camera is connected has been proposed. Such association between the image and unique ID is executed on the digital camera side upon recording an image or the like. Japanese Patent Laid-Open No. 2004-112602 has proposed a digital camera which calculates a unique ID based on a file path of data, and manages the data. Also, Japanese Patent Laid-Open No. 2002-259332 has proposed a technique for recording identification information unique to a device in data.
Furthermore, Japanese Patent Laid-Open No. 2002-271672 describes a technique which acquires identification information unique to a device and image information from another electronic device, generates image information that describes the identification information, and outputs that image information. Japanese Patent Laid-Open No. 2002-259668 discloses a technique which generates and outputs an image file which describes an identifier of an electronic device itself, and a technique which generates and outputs an image file that describes an identifier set by the user.
However, since the technique of Japanese Patent Laid-Open No. 2004-112602 calculates a unique ID based on the file path of data, identical data that have different file path configurations will be assigned unique IDs. That is, a plurality of unique IDs may be assigned to identical image information. Since the technique of Japanese Patent Laid-Open No. 2002-259332 associates the unique ID of the device to data, the device can be specified from the data, but the data cannot be uniquely specified.
Furthermore, the technique described in Japanese Patent Laid-Open No. 2002-271672 contemplates setting of the unique ID for image information, but does not contemplate the re-setting of a unique ID for an image that has already been set with the unique ID. For example, when an edit operation is made to change the image contents, if the unique ID is maintained even though the image information has changed, the same unique ID is assigned to different images. Also, when processing such as rotation of an image that does not practically change the image contents is applied, if the unique ID is re-assigned, a plurality of unique IDs are assigned to an identical image. The technique described in Japanese Patent Laid-Open No. 2002-259668 can specify the electronic device but cannot specify an image, and does not assume assignment of unique IDs upon image editing.
Therefore, with the general unique ID assignment method to image information, identical data may be transferred a plurality of times with an external device that manages the holding state of image files recorded in the digital camera. Also, an image file that requires transfer may fail to transfer. As a result, image file management efficiency and reliability of the digital camera and external device are impaired. The same issue applies to still image files, moving image files, or audio files. That is, it is required to prevent identical data from being transferred a plurality of times with an external device which manages the reception state of data files recorded in a recording apparatus using the unique IDs of data files.